High energy non-aqueous lithium sulfur (Li—S) redox flow batteries are of interest, particularly for stationary applications. However, the presence of insoluble short-chain polysulfides largely sacrifices the theoretically high energy opportunity due to deposition of Li2S2/Li2S onto the current collectors (for example, graphite felt). In addition, the unstable interface between the conventional electrolyte and the lithium metal anode surface also limits the long-term cycling performance of the redox flow batteries.